Preparation of benzene 1, 4-bis (phenylphosphinic acid)



United States Patent 3,341,576 PREPARATION OF BENZENE 1,4-BIS (PHENYLPHGSPHINIC ACID) David L. Herring, Riverside, Califi, assignor to the United States of America as represented by the Secretary of the Navy No Drawing. Filed July 17, 1963, Ser. No. 295,854

1 Claim. (Cl. 260-500) The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a general method for the preparation of substituted aryl diphosphines. These materials are useful intermediates in the synthesis of new and useful thermally stable, thermoplastic and thermosetting polymeric materials, which may be moulded, cast or extruded.

A previous method is reported by J. Chatt and F. A. Hart, JCS. 1378 (1960) which can be described by the following equations:

However, the above method is tedious, costly and the yield or product is low. Whereas, the method of the present invention is less complicated, inexpensive and the yields of product are higher.

An object of the invention is to provide a method for the preparation of substituted aryl diphosphines.

Another object of the invention is to provide a method for preparing a new intermediate compound A further object of the invention is to provide a method for preparing a new thermally stable compound P- B 5 (OH)C6H4P(0) s 5 Other objects and many of the attendant advantages of this invention will become readily appreciated as the same becomes better understood by reference to the following detailed description.

The present invention is disclosed in the following procedure for preparing the new compound benzene 1,4- bis(phenyl phosphinic acid) of the formula All reactions were carried out in an inert atmosphere with conventional equipment and reagent grade starting materials. To 64.0 g. of n-butyllithiurn in 450 m1. of pentanehexane mixture, a solution of 600 ml. of hexane containmg 94.0 g. of p-dibromobenzene was added dropwise with stirring over the course of 1 /2 hours. The resulting mixture was heated at 50-55" C. for 48 hours. During the heating process p-dilithiobenzene formed in about 50% yield. [The compound used in the next step of the reaction was formed in the following manner: To 357.8 g. (2.0 moles) of C H PCl was first added 1500 ml. of dry n-hexane; then, with vigorous stirring, 292.0 g. (4.0 moles) of (C H NH was added dropwise over the course of 1 /2 hours. After Patented Sept. 12, 1967 the addition was completed, the resulting mixture was filtered to remove the by product (C H NH-HCl, which was then extracted with three 350 ml. portions of n-hexane. The filtrate and n-hexane washings were combined and fractionally distilled to yield 248.3 g. (81%) of water-white calcd. for C H PNCl: N, 6.5, found: N, 6.1]. To the slurry of p-dilithiobenzene, 215 g. of

was added dropwise over the course of an hour. After the addition was completed, the resulting mixture was heated at 5055 C. for 3 hours, then filtered. The insoluble material was extracted with three ml. portions of boiling n-hexane. The filtrate and washings were combined, and 73.1 g. of (C H NH was added to convert any remaining starting material to e 5 2 5)2]2 The precipitate of (C H NH-HCl which formed was removed by filtration and the resulting filtrate was frac tionally distilled to remove unreacted starting material as s s 2 5)2]2 (B.P. 82104 C./0.8-10 mm.) leaving a liquid residue containing P- e 5 [N(C2H5)2]C6H4P 2 5)2] e 5 (i.e. 1,4-bis(phenyl diethylamino phosphino)benzene). Treating a sample of the P 6 5 2 5)2] 6 4 2 5)2] s s 4 where M=alkali metal, MgX or HgX; P=phosphorus; then fractionally distilling the combined filtrate and R=H, alkyl, aryl; R=alkyl or aryl; X=halogen. extract to recover the compound The intermediate compound (I) may be reacted with anhydrousHCl to yield, for example, derivatives such as pficslilsp [NQCZHQZ] d i :1 5)2] e 5 p 6 5 (C1) csHP (C1) C6115 5 (b) reacting sai recovere compoun a family of compounds useful in the formation of (P-N) PC6H5P [N(C2H5)2] CGHaP [N(C2H5)2] CGHS d (P-B) bonded polymers. Compound 11, the aryl with dilute HCl followed by reaction with 30% H substituted diphosphonic acid represents a family of comat form a Water Insoluble, cmam pounds useful in the formation of polyesters, poly anhy- 1O Cred, Q'Q q (hides and polymers having the i k (c) purifying said crude acid by recrystallization from R a member of the group consisting of ethanol and 1 N Q @l nitrobenzene to yield a pure product of the formula 1 l P 6 (OH)CGH4P(O) l e s having a melting point of 330-333 0. Where R=alkyl, aryl or aryloxy, R=H, alkyl, or aryl. References Cited Obviously many modifications and yariations of the UNITED STATES PATENTS present invention are possible in the light of the above teachings. It is therefore to be understood that within 2,934,564 4/1960 f' et a1 the scope of the appended claim the invention may be 3,147,313 4/1964 Hsleh 260-500 practiced otherwise than as specifically described. 3,157,694 11/1964 Harwood 260-932 What is claimedis; 3,189,564 6/1965 Washburn et al. 260 -551 The synthesis of benzene 1,4-bis(phenyl phosphinic FOREIGN PATENTS acid) which comprises:

(a) slowly adding two molar quantities of 921463 3/1963 Great Bmam' OTHER REFERENCES 0 H P(Cl)N(C H) 6 5 2 5 2 Frank: Chem. Rev., vol. 61 (1961), p. 394.

to a pentane-hexane slurry of one molar quantity of i n p-dilithiobenzene and heating the resulting mixture 3 gfgg fg gigg compounds (1950) at -55 C. to form a liquid reaction product which is freed from both insoluble starting materials and LEON ZITVER Primary Exam-"en insoluble reaction by-products by filtration and extraction of any solid materials with boiling n-hexane, EVANS, Assistant Examme" 

